Spinneret with inert gas metering ring

ABSTRACT

A conventional round spinneret is blanketed with inert gas by providing a passage for the gas through the spinning pack assembly to the lower face of the spinneret and providing a metering ring encircling the filament array and in contact with the lower face of the spinneret. In the upper surface of the ring is a groove for distributing gas around the filament array and a plurality of vertical holes connect the groove with the underside of the ring. Below the metering ring is a spinneret retainer ring with a groove in its upper surface in communication with the vertical holes in the metering ring. The retainer ring has a lip formed in its inner periphery which in conjunction with the metering ring forms an open slot through which inert gas passes laterally towards the filament array. The vertical holes are sized to provide an appreciable pressure drop through each hole while avoiding turbulent flow into the retainer ring groove which must diffuse the individual streams of gas and deliver the gas in a smooth uniform stream to the filaments through the slot.

United States Patent [191 Akers, II et a1.

Martinsville, Va.; Stanley Carleton Crewe, Signal Mountain, Tenn.

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

22 Filed: Oct. 27, 1972 21 Appl. No.: 301,536

[52] US. Cl 425/72, 264/176 F [51] Int. Cl DOld 3/00 [58] Field of Search 425/72, 464; 264/176 F,

[56] References Cited UNITED STATES PATENTS 8/1941 Bradshaw 425/72 X 9/1973 Heckrotte et al. 264/176 F X Primary E.raminerRobert D. Baldwin 1 June 4, 1974 [57] ABSTRACT A conventional round spinneret is blanketed with inert gas by providing a passage for the gas through the spinning pack assembly to the lower face of the spinneret and providing a metering ring encircling the filament array and in contact with the lower face of the spinneret. In the upper surface of the ring is a groove for distributing gas around the filament array and a plurality of vertical holes connect the groove with the underside of the ring. Below the metering ring is a spinneret retainer ring-with a groove in its upper surface in communication with the vertical holes in the metering ring. The retainer ring has a lip formed in its inner periphery which in conjunction with the metering ring forms an open slot through which inert gas passes laterally towards the filament array. The vertical holes are sized to provide an appreciable pressure drop through each hole while avoiding turbulent flow into the retainer ring groove which must diffuse the individual streams of gas and deliver the gas in a smooth uniform stream to the filaments through the slot.

4 Claims, 3 Drawing Figures l SPINNERET WITH INERT GAS METERING RING BACKGROUND OF THE INVENTION The present invention relates to the production of synthetic polymeric filaments and particularly to apparatus for blanketing the exposed face of a spinneret with an inert gas.

In melt spinning operations, some of the fiber forming material tends to build up on the spinneret face around each extrusion orifice and oxidize into a hard deposit which eventually interrupts the spinning process. Various devices have been proposed for directing inert gas across the spinneret face in an effort to exclude oxygen. For example, in Ferrier et al., U. S. Pat.

No. 3,229,330, various arrangements are shown for' providing hot inert gas to the region of the spinneret face through distribution channels surrounding the filament spinning pack including various arrangements of gas distribution channels in the spinneret retainer, the pack assembly, and the space between the two. It can be appreciated that when a large spinning operation may include many hundreds of spinning pack assemblies, it is desirable that the parts be simple in design so as to be inexpensive to fabricate and clean. The internally drilled passages of Ferrier et al. are relatively difficult to fabricate and some arrangements are not easily inspected for cleanliness.

SUMMARY OF THE INVENTION An apparatus for blanketing the face of a spinneret with inert gas is incorporated into the spinneret assembly by adding a metering ring between the spinneret and its retainer ring. In particular, the spinneret assembly contains a spinneret plate having a lower face with an orifice array through which filaments are extruded and the plate is held in place by a retainer ring which has an upper surface with a continuous groove and terminates in a lip at its inner periphery. A metering ring surrounding the orifice array is located between the lower face of the spinneret and the retainer ring and has its upper and lower surfaces connected by a continuous groove in the upper surface in communication with a plurality of vertical holes leading through the lower surface. Means are provided for supplying inert gas to the continuous groove in the metering ring. The retainer ring lip and the lower surface of the metering ring form an open slot through which inert gas passes laterally toward an array of filaments extruded through the spinneret orifices.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross-sectional view through the center of a spinning pack assembly showing the invention.

FIG. 2 is a top view of the metering ring of FIG. 1.

FIG. 3 shows an alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS In the drawing, the spinning pack assembly 1 is shown schematically. The lower element of the pack assembly is spinneret 2 having holes through which polymeric filaments 3 are extruded. The internal details of the polymer supply are immaterial to this case and are omitted. Referring to FIG. 1, inert gas is supplied through the spinning block (not shown) to metering orifice 4 whichforms a tight seal between the gas supply and the spinning pack. Inert gas passage 5 leads the gas through the spinning pack to the underside of the spinneret. Metering ring 6 surrounds the filament array below the spinneret face and has a continuous circular groove 7 cut into its upper surface. A series of vertical holes 8 connect groove 7 with the underside of ring 6 and meter inert gas into continuous plenum groove 9 in the spinneret-retainer 10 below. The gas then passes laterally toward the filament array through gap or slot 11 formed between the lower surface of metering ring 6 and lip 12 formed at the inner periphery of the spinneret retainer.

At least a portion of metering ring 6 must be sufficiently strong to support the upward force exerted by spinneret retainer 10 against spinneret 2 which supports the weight of spinning pack 1 and seals the polymer and inert gas supplies to their respective sources against their respective pressures. Holes 8 are sufficiently small so as to produce an appreciable pressure drop through each hole, thus forcing the flowing gas to distribute itself relatively uniformly around groove 7. However, holes 8 should not be so small that the velocity of the gas through each is excessive, giving high turbulence in plenum groove 9, the purpose of which is to diffuse the discrete streams of gas entering through holes 8 and to deliver the gas in a relatively smooth uniform stream to the filaments through gap 11.

In FIG. 3, metering ring 6 is shown in an alternative form which may be stamped from sheet metal in quantity at lower cost than the machined metering ring 6 of FIGS. 1 and 2. In this form, (FIG. 3) the continuous groove 7 takes the form of an indentation with a corresponding protrusion which extends downwardly into retainer groove 9. The thinness of the metal and its configuration comprises the ring assembly and allows inert gas to be delivered through gap 11 closer to the lower face of spinneret 2 than in the arrangement of FIG. 1. If it is desired to deliver inert gas directly against the lower face of spinneret 2, flange 15 of metering ring 6 may be shortened and lip 12 of spinneret retainer 10 may be extended so that inert gas passing from plenum groove 9 toward the filament array first passes through a gap formed between the inside surface of lip 12 and the contiguous surface of metering ring 6 and then passes laterally toward the filament array through a gap 11 between lip 12 and the lower surface of spinneret 2. Flange 13 may be added at the outer periphery of metering ring 6 to mate with a chamfer of spinneret 2 for positive concentric alignment of metering ring 6 with the filament array. Shoulder 14 of spinneret retainer 10 may then mate with the outer periphery of the ridge on the underside of metering ring 6 caused by pressing groove 7 into the upper surface and thus align spinneret retainer 10 concentrically with the filament array.

Metering ring 6 and the unique features of spinneret retainer 10 are easy to fabricate and are compatible with conventional designs of spinning packs and spinneret retainers. Metering ring 6 is sufficiently rugged to resist damage in assembly and disassembly and the grooves and holes in both the metering ring and spinneret retainer can be readily cleaned and inspected for freedom from dirt and obstructions.

What is claimed is:

1. An apparatus for blanketing the face of a spinneret with inert gas comprising: a spinneret assembly containing spinneret plate having a lower face with an orifice array through which filaments are extruded, said plate being held in place by a retainer ring surrounding said array, said retainer ring having an upper surface and an inner periphery, said upper retainer ring surface having a continuous groove therein, said retainer ring terminating in a lip at its inner periphery; a metering ring surrounding said array located between the lower face of the spinneret and the upper surface of the retainer ring, said metering ring having upper and lower surfaces connected by a continuous groove in communication with a plurality of vertical holes leading through the lower metering ring surface; and means for supplying inert gas to the continuous groove in the metering ring, the retainer ring lip and the lower surface of the metering ring forming an open slot surrounding the array of orifices, said slot being in communication with the continuous groove in the retainer ring.

2. The apparatus as defined in claim 1, said continuous groove in said metering ring being in the form of an indentation in the upper surface of the ring with a corresponding protrusion in the lower surface of the ring, said protrusion extending into the groove formed in the upper surface of the retainer ring.

3. The apparatus as described in claim 1, said vertical holes being equispaced radially and equispaced from each other in said metering ring.

4. The apparatus as described in claim 1, said groove being circular. 

1. An apparatus for blanketing the face of a spinneret with inert gas comprising: a spinneret assembly containing spinneret plate having a lower face with an orifice array through which filaments are extruded, said plate being held in place by a retainer ring surrounding said array, said retainer ring having an upper surface and an inner periphery, said upper retainer ring surface having a continuous groove therein, said retainer ring terminating in a lip at its inner periphery; a metering ring surrounding said array located between the lower face of the spinneret and the upper surface of the retainer ring, said metering ring having upper and lower surfaces connected by a continuous groove in communication with a plurality of vertical holes leading through the lower metering ring surface; and means for supplying inert gas to the continuous groove in the metering ring, the retainer ring lip and the lower surface of the metering ring forming an open slot surrounding the array of orifices, said slot being in communication with the continuous groove in the retainer ring.
 2. The apparatus as defined in claim 1, said continuous groove in said metering ring being in the form of an indentation in the upper surface of the ring with a corresponding protrusion in the lower surface of the ring, said protrusion extending into the groove formed in the upper surface of the retainer ring.
 3. The apparatus as described in claim 1, said vertical holes being equispaced radially and equispaced from each other in said metering ring.
 4. The apparatus as described in claim 1, said groove being circular. 